Predators Hunt for a Balanced Diet

ScienceDaily (Jan. 10, 2012) — Predators select their prey in order to eat a nutritionally balanced diet and give themselves the best chance of producing healthy offspring.

A University of Exeter and Oxford-led study published in Proceedings of the Royal Society B shows for the first time that predatory animals choose their food on the basis of its nutritional value, rather than just overall calorie content.

An international team of scientists from the Universities of Exeter and Oxford in the UK, University of Sydney (Australia), Aarhus University (Denmark) and Massey University (New Zealand) based their research on the ground beetle, Anchomenus dorsalis, a well-known garden insect that feasts on slugs, aphids, moths, beetle larvae and ants.

The team collected female beetles from the wild and split them into two groups in the laboratory. Half of the beetles were offered a choice of foods, some that were high in protein and some that were high in fat. The other half were not given a choice of what to eat: some were only given food that was higher in protein and others just had higher-fat foods, none of which provided the right nutritional balance. The beetles that were provided with a range of foods selected the balance of protein and fat that was optimal for producing healthy eggs. These beetles produced more eggs than the beetles that did not have the right nutritional balance.

Continued at: http://www.sciencedaily.com/releases/2012/01/120110192942.htm